1. Technical Field
The present disclosure relates to systems, devices and methods for performing a medical procedure. More particularly, the present disclosure relates to electrosurgical systems including a data acquisition module operably associated with an energy applicator and methods of directing energy to tissue.
2. Discussion of Related Art
Electrosurgery is the application of electricity and/or electromagnetic energy to cut, dissect, ablate, coagulate, cauterize, seal or otherwise treat biological tissue during a surgical procedure. When electrical energy and/or electromagnetic energy is introduced to tissue, it produces excitation of molecules, which results in the generation of heat. Generally, electrosurgery utilizes an electrosurgical generator operable to output energy and active and return electrodes that are electrically connected via a cable assembly to the generator. Electrosurgery can be performed using either a monopolar or a bipolar instrument.
Electrosurgical generators are employed by surgeons in conjunction with electrosurgical instruments to perform a variety of surgical procedures. An electrosurgical generator generates and modulates electrosurgical energy which, in turn, is applied to the tissue by an electrosurgical instrument.
Electrosurgical generators may provide energy delivery in two types of modes: continuous and pulsed. The current output of electrosurgical generators can be modulated to deliver different waveforms to the tissue, depending on the mode. As the output waveforms change, so does the corresponding tissue effect. The continuous mode of current output is often referred to as the “cut” mode and delivers electrosurgical energy as a continuous sinusoidal waveform. In addition to the pure “cut” mode, there are often blended modes that modify the degree of current interruption to achieve varying degrees of cutting with hemostasis. Interrupted current generally is quantified by expressing the “on” time as a percentage of the total time, creating a value called the duty cycle.
The basic purpose of both monopolar and bipolar electrosurgery is to produce heat to achieve the desired tissue/clinical effect. In monopolar electrosurgery, devices use an instrument with a single, active electrode to deliver energy from an electrosurgical generator to tissue, and a patient return electrode or pad that is attached externally to the patient (e.g., a plate positioned on the patient's thigh or back) as the means to complete the electrical circuit between the electrosurgical generator and the patient. When the electrosurgical energy is applied, the energy travels from the active electrode, to the surgical site, through the patient and to the return electrode. In bipolar electrosurgery, both the active electrode and return electrode functions are performed at the site of surgery. Bipolar electrosurgical devices include two electrodes that are located in proximity to one another for the application of current between their surfaces. Bipolar electrosurgical current travels from one electrode, through the intervening tissue to the other electrode to complete the electrical circuit. Bipolar instruments generally include end-effectors, such as grippers, cutters, forceps, dissectors and the like.
Tissue effects that can be achieved with electrosurgery can be roughly divided into three basic groups: cutting, fulguration, and desiccation. In addition to output modes and power settings, electrosurgical tissue effects depend on a number of other factors. The size and geometry of the electrodes delivering the energy play a role in achieving the desired surgical effect. Using electrosurgical instruments to ablate, seal, cauterize, coagulate, and/or desiccate tissue may result in some degree of thermal injury to surrounding tissue. For example, electrosurgical desiccation may result in undesirable tissue damage due to thermal effects, wherein otherwise healthy tissue surrounding the tissue to which the electrosurgical energy is being applied is thermally damaged by an effect known in the art as “thermal spread”. During the occurrence of thermal spread excess heat from the operative site can be directly conducted to the adjacent tissue, and/or the release of steam from the tissue being treated at the operative site can result in damage to the surrounding tissue. The duration of the activation of the generator is directly related to the heat produced in the tissue. The greater the heat produced, the more the potential for thermal spread to adjacent tissues.
It has been well established that a measurement of the electrical impedance of tissue provides an indication of the state of desiccation of the tissue, and this observation has been utilized in some electrosurgical generators to automatically terminate the generation of electrosurgical power based on a measurement of tissue impedance. At least two techniques for determining an optimal amount of desiccation are known by those skilled in this art. One technique sets a threshold impedance, and terminates electrosurgical power when the measured tissue impedance crosses the threshold. A second technique terminates the generation of electrosurgical power based on dynamic variations in the tissue impedance.
Currently available systems and methods for controlling an electrosurgical generator during electrosurgery may include a clinician monitoring and adjusting, as necessary, the amount of energy delivered to a tissue site through current, voltage, impedance, and/or power measurements such that an appropriate tissue effect can be achieved at the tissue site with minimal collateral damage resulting to adjacent tissue. These systems and/or methods typically require a clinician to translate the desired tissue effect to a power setting on an electrosurgical generator and, if necessary, adjust the power setting to compensate for tissue transformations (e.g., desiccation of tissue) associated with the electrosurgical procedure such that a desired tissue effect may be achieved.
As can be appreciated, limiting the possibility of thermal spread or the like during an electrosurgical procedure reduces the likelihood of unintentional and/or undesirable collateral damage to surrounding tissue structures which may be adjacent to an intended treatment site. Controlling and/or monitoring the depth of thermal spread during an electrosurgical procedure may aid a clinician in assessing tissue modification and/or transformation during the electrosurgical procedure.